As for a communication cable transmitting a signal to a computer, various communication devices, and the like, or a power cable transmitting electric power (hereinafter, the communication cable and the power cable are collectively called as a cable), a signal transmitted through such a cable may be affected by noise including an electromagnetic field which flows from an external electronic device. In addition, a signal itself, which is transmitted through a cable, may emit noise, including an electromagnetic field to the outside, and such emitted noise may cause an effect to an external electronic device. Particularly, as a frequency of a signal transmitted through a cable is higher, such a signal may be more affected by noise which flows from the outside and further it may emit more noise to the outside.
To shield such noise, a conventional method surrounds a cable with a conductive shield layer. However, when a frequency of a signal transmitted through a cable is high, noise emitted from an inside of the cable may not be effectively shielded with only such a conductive shield layer. This is because that noise, which should be shielded, includes a lot of harmonic components as a frequency of a signal is higher. Consequently, there is a need for technology which is capable of effectively shielding the inflow and emission of noise including an electromagnetic field even when a frequency of a signal transmitted through a cable is high.
There is another conventional method for shielding noise, in which a ferrite core for filtering noise is applied to an end part of a cable. However, in the another conventional method employing such a ferrite core for filtering noise, there are difficulties in application in that a ferrite core for filtering noise, which has impedance corresponding to a characteristic of a cable, should be selected and applied to the cable, and further the ferrite core itself has a thick thickness.
Meanwhile, among technologies for shielding noise such as the electromagnetic field as described above, there may be a method using a magnetic shielding material, which contains a nano-crystalline metal ribbon having high permeability.
However, when an alternating current (AC) magnetic field is applied to the nano-crystalline metal ribbon contained in the magnetic shielding material, an eddy current may be generated on a surface of the nano-crystalline metal ribbon. The generated eddy current may cause problems including generation of heat, and the like.
To reduce an effect due to such an eddy current, there is a method of flaking the nano-crystalline metal ribbon. Through the flaking, the nano-crystalline metal ribbon may be broken up and divided into a plurality of fine pieces. When the nano-crystalline metal ribbon is divided into the plurality of fine pieces, an effect resulting from an eddy current may be reduced. This is because magnitude of an eddy current is proportional to a surface area of a position at which the eddy current is generated, and, when the nano-crystalline metal ribbon is divided into the plurality of fine pieces, a surface area of each of the fine pieces, at which the eddy current is generated, is reduced in comparison with that of the nano-crystalline metal ribbon before the flaking is performed thereon. However, when the nano-crystalline metal ribbon is divided into the plurality of fine pieces through the flaking, a crack, that is, a gap provided each between the plurality of fine pieces is significantly less than a size of each of the plurality of fine pieces, and thus adjacent fine pieces among the plurality of fine pieces may flow to come into contact with each other. When the adjacent fine pieces come into contact with each other, the surface area of the position, at which the eddy current is generated, may be increased again. This may cause an increase of the effect resulting from the eddy current.
Further, as for a conventional magnetic shielding material containing a nano-crystalline metal ribbon on which the flaking is performed, there is difficulty in securing flexibility suitable for winding a cable and the like in the form of a roll.
Therefore, when a magnetic shielding material containing a nano-crystalline metal ribbon is applied to a target including a cable and the like, technologies which are capable of preventing shielding performance of the magnetic shielding material from being degraded even when flaking is performed on the nano-crystalline metal ribbon and at the same time reducing an effect resulting from an eddy current generated at the nano-crystalline metal ribbon, and further enabling the magnetic shielding material to be easily wound on the cable and the like are required.